Sean FitzPatrick was arrested at his home in County Wicklow. Photograph: Arnold Bell/PA

The former chairman of one of the banks at the heart of Ireland's financial crisis has been arrested. Sean FitzPatrick, the ex-head of Anglo Irish Bank, is being questioned by the Garda Siochana over allegations of financial irregularities.

He stepped down as the bank's boss in December 2008 after admitting he had hidden millions of euros in personal borrowings from Anglo Irish. Anglo Irish's demise symbolised the collapse of the "Celtic Tiger" economy in the Republic.

Last year, the Dublin-based bank reported the biggest loss in Irish corporate history when it made a loss of €4.1bn (£3.7m) in the six months to March on the back of large impairments on its property loans to developers. Its latest set of results, due to be published soon, are expected to be much worse.

The bank was one of the star performers of Ireland's economy during the country's property boom, lending billions of euros for development in Ireland and Britain.

It was nationalised by the Fianna Fáil/Green party government in 2009 after it threatened to collapse in the face of a property crash.

Aside from the concealment of directors' loans, other scandals to afflict the bank included a scheme to allegedly give artificial support to the bank's share price and the recording of a huge loan from another bank as a customer deposit.

Last week FitzPatrick told the bank he could not repay €70m (£63m) he owes in unpaid loans.

As a result, the bank has started legal action against him in an attempt to recover the debt.

FitzPatrick was arrested at his home in Greystones, County Wicklow, by the Garda Bureau of Fraud Investigation on Thursday. His house was also searched.